Special protecting material for oversized round billet made of medium carbon steel for continuous casting mold

Abstract

The invention discloses a special protecting material for an oversized round billet made of medium carbon steel for a continuous casting mold. The protecting material comprises the following materials by mass percent: 40.0% of pre-melting material, 16% of albite in powder, 3% of cement clinker, 12.0% of sodium carbonate, 5.5% of fluorite, 1% of iron oxide red, 2.5% of lithium carbonate, 14% of black carbon and 6% of 85flake graphite. The protecting materials produced by Henan Xibao Metallurgy Materials Group Co., Ltd can be melted uniformly in a crystallizer with less slag circles and have good spreadability and good thermal insulation performance, clots do not exist, the thickness of melt cinders is 10 to 12 mm at normal pulling speed, the steel consumption for each ton of protecting materials is 0.35 kg to 0.45 kg, the heat transmission at periphery in the crystallizer is stable and uniform, alarm does not exist, and cleaning free rate for surfaces of casting blanks can reach more than 98%, so that requirements for producing large-sized round billets for factories can be met.

Description

technical field [0001] The invention belongs to the technical field of metallurgical auxiliary materials, in particular to a special continuous casting crystallizer protection material for carbon steel in a super large round billet. Background technique [0002] Modern seamless steel pipes adopt advanced steelmaking technology and refining methods outside the furnace, and adopt technologies such as protective pouring and electromagnetic stirring during continuous casting, so the yield of finished products reaches more than 98%, and the outer surface has no cracks, scars, or slag inclusions , depressions, bubbles, and other defects such as mechanical scratches and indentations with a depth greater than 1.5mm; the cracks, pores, segregation and inclusions inside the tube blank, and the state of the solidified structure can also meet the requirements of the rolled tube. Therefore, the round billet has become the first choice for the pipe billet used in the modern seamless steel...

AI Technical Summary

Problems solved by technology

②The billet shell is in good contact with the crystallizer wall, the heat transfer capacity is strong, the billet shell grows quickly and relatively uniformly, the probability of cracks in the primary billet shell is small, but the rejoining ability between the billet shells is poor, and it is easy to Pull-off or breakout occurs

③ Due to the serious segregation of P, S and C in molten steel, the internal structure of the slab is segregated and loose; if the cooling intensity of the crystal water is too large, internal cracks are prone to appear

[0005] The reason why the external dimension of the super large continuous casting round billet exceeds the standard is relatively simple, mainly affected by the equipment precision and cooling process, but it is not easy to control. Therefore, only by taking effective measures to improve the equipment precision and control the casting billet cooling process can the casting be avoided. The dimensions of the billet exceed the standard